The present invention relates generally to clutches and more specifically to a fluid operated clutch assembly having a plurality of interleaved clutch plates, commonly referred to as a disc pack, for use with diesel engine blowers and the like.
Two-cycle diesel engines are commonly utilized in trucks and other vehicles. Diesel engines of this type normally require pressurized air during start-up and under normal operating conditions. As a result, a supercharging blower is usually provided to generate and supply a predetermined level of pressurized air to the engine. Additionally, a turbocharger is also often provided to further increase the level of pressurized air supplied to the engine. In the past, the blower has been driven by a direct connection to a mechanical output of the engine, such as a gear train connected to a crankshaft of the engine, while the turbocharger has been driven by exhaust gases from the engine. Accordingly, both of these devices have been continuously operated while the engine is running. However, it has been found that it is undesirable to operate both the blower and the turbocharger under certain operating conditions of the engine, operating conditions in which the turbocharger alone is the more efficient means of supplying pressurized air to the engine. The factors which contribute to these operating conditions include the load on the engine, the position of the throttle, the level of smoke and other emissions from the engine, and the like. Therefore, it would be desirable to provide a clutch assembly for selectively connecting the blower to the mechanical output of the engine. Such a clutch assembly would preferably be compact, have low parasitic drag, and have a normally engaged configuration such that activation by a motive medium disengages the clutch. Failure of the motive medium or other mechanisms in the clutch would therefore maintain engagement between the blower and the mechanical output of the engine.